Yeasts and molds are eukaryotic microorganisms. They are ubiquitous in natural environments, namely, soil, air, water, and plant surfaces. Because of their heterotrophic nature and their ability to adapt to a wide range of environmental conditions, these microbes are frequently encountered as an expensive nuisance in and on various commodities including food ingredients, processed foods, beverages, inadequately cleaned food processing equipment, and food storage facilities. In addition, some yeasts and molds possess potential hazard to human and animal health. For example, numerous molds produce mycotoxins and some yeasts and molds are responsible for human and animal infections.
Yeast or mold contamination in food and other commodities can result in substantial economic losses for the producer, the processor, and the consumer. Rapid and accurate determinations of yeast and/or mold contamination in a commodity (such as, food ingredients, processed foods, and beverages), are important for the production of high-quality food products in the food industry.
Current practices for routine determination of yeasts and molds in a food commodity rely largely on conventional culturing techniques for enumerating viable fungal cells on semi-solid agar media. These methods, although widely accepted, have a number of disadvantages in that they are, in general, labor intensive and give low reproducibility. In addition, a common problem encountered in the traditional methods is that the spreading type of mycelial growth of certain molds often over-runs nearby colonies and prevents accurate enumeration of the viable cells in a sample.
Most importantly, most of these methods require a 5 day incubation period at 25° C. before accurate quantitative results can be obtained. The long incubation period of these methods can require that food products be stored for several days, until the presence or concentration of contaminating yeasts and/or molds is finally known. Thus, there is a need for improved tests and related materials. If the test procedures could be simplified, and test results obtained in a shorter period of time, it would allow manufacturers to release products; thereby reducing storage costs without sacrificing product quality and integrity.